Thoriz Pelagius Septim (3E 119 - 3E 153), more commonly known as Pelagius Septim III or Pelagius the Mad, was Jarl of Solitude and High King of Skyrim from 3E 137 until 3E 145,[1][2] when he was crowned Emperor of Tamriel after the death of his father Magnus Septim.[3] Legend accuses Pelagius III of murdering Magnus, but this is generally dismissed as false, both because Pelagius seldom visited the Imperial City,[4] and it is documented he was present in Solitude at the time of his father's death.[3]

Already infamous in Skyrim for his eccentricities, Pelagius III's mind deteriorated dramatically during his reign over Tamriel.[3] He embarrassed dignitaries, offended his vassal kings, and, on one occasion, marked the end of a grand ball by attempting to hang himself.[4] His madness is speculated to have been caused by Potema the Wolf Queen, whose own insanity was said to have been infused in Castle Solitude, infecting the next king to rule there.[5]

The madness of Pelagius eventually cost him the throne. Empress Katariah, a shrewd diplomat hand-selected by Magnus to be Pelagius' wife in order to hide his son's problems, was made Empress Regent of Tamriel two years into his reign. Pelagius III, meanwhile, was sent to a series of healers and asylums until his death at the age of thirty-four.[4] He died on a warm night in Sun's Dawn after a brief fever in his cell, at the Temple of Kynareth on the Isle of Betony. The 2nd of Suns Dawn, which may or may not be the anniversary of his death (records are not clear), is celebrated as Mad Pelagius Day, the time when foolishness of all sorts is encouraged.[3] The Temple of Kynareth in which Pelagius died was destroyed shortly after his death.[6] A group of heretics known as the Apostles later took the stones of the Temple, and rebuilt it in exact detail in the Shivering Isles. It is now known as the Howling Halls because it is said that Pelagius' screams can still be heard.[6] The pelvis of Pelagius was discovered in these ruins in 3E 433, and was put on display in Crucible.[7]

Even in death, Pelagius was trapped by his own madness. It is said that his ghost went on to haunt the Pelagius Wing of the Blue Palace in Solitude, which was locked up and left alone for centuries.[1] In 4E 201, the Last Dragonborn received the hip bone of Pelagius in Solitude from Dervenin, the Priest of Mania, and entered the Pelagius Wing, where he was transported into the dead emperor's mind and found Sheogorath. The Mad God had retired within Pelagius' mind to try and cheer the dead emperor up, but to no avail. The Prince tasked the Last Dragonborn with cleansing Pelagius' mind of paranoia, suspicion, self-doubt, anger, and torment using the Wabbajack. This finally allowed Pelagius some peace, and Sheogorath and the Last Dragonborn left him to his rest.[8]